Lecture 5: Ionization & Radioactivity

Flashcards covering key terms and definitions from the lecture on Radiologic Physics, Ionization, and Radioactivity.

Ionization

A process of removal of an electron from its shell or orbit in an atom.

Positive Ion

The remaining atom after it gives away an electron, having a net electric charge of +1.

Negative Ion

A free electron released during ionization, having a net electric charge of -1.

Ion Pair

Together, the ionized atom (positive ion) and the released electron (negative ion) are called an ion pair.

Isotopes

Any element that has the same number of protons but a different number of neutrons, meaning atoms with the same atomic number but different atomic mass.

Isotones

Any element that has the same number of neutrons but different numbers of protons, meaning atoms with different atomic number and different atomic mass BUT a constant value for A-Z.

Isobars

Any element that has different numbers of neutrons and different numbers of protons, meaning atoms have the same atomic mass but different atomic number, or the same number of nucleons (p+n).

Isomers

Atoms that have the same atomic number and same atomic mass, but exist at different energy levels.

Radioactivity

The process where an unstable nucleus emits particles and energy to transform itself into another atom to gain stability.

Radioactive Decay / Radioactive Disintegration

The process by which an unstable nucleus emits particles and energy to gain stability.

Radioisotopes

Unstable isotopes that emit particles and energy during radioactive decay.

Radioactive Half-Life (T ½)

The time required for a quantity of radioactivity to be reduced to one-half its original value.

Ionizing Radiation

A type of radiation that produces ions (negative and positive charged particles), usually by ejecting an orbital electron of an atom, making the atom unstable.

Particulate Radiation

A category of ionizing radiation that includes Alpha particles and Beta particles, differing in mass, energy, velocity, charge, and origin when acting on biological tissue.

Electromagnetic Radiation (Ionizing)

A category of ionizing radiation that includes X-rays and Gamma rays, differing in mass, energy, velocity, charge, and origin when acting on biological tissue.

Alpha Particle Emission

Particulate radiation consisting of 2 protons and 2 neutrons (or a Helium atom), originating from the nucleus of heavy elements, with an atomic mass of 4 amu, a charge of +2, and a smaller range than beta emission.

Beta Particle Emission

Particulate radiation consisting of high-speed electrons, originating from the nucleus of unstable radioactive elements, with an atomic mass of 1 amu, a charge of -1, and a larger range enabling it to ionize more than alpha particles.

Gamma Rays Emission

Electromagnetic radiation emitted along with alpha and beta particle emission, originating from the nucleus by a natural process, with no mass, no charge (photon), unlimited range in matter, and more penetrability than X-rays.

X-Rays Emission

Electromagnetic radiation that is man-made (artificial), originating from electrons (outside the nucleus), with no mass, no charge (photon), an unlimited range in matter, and less penetrability than gamma rays.

Photon

The unit of gamma rays and X-rays, characterized by having no mass and no charge.